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Niles
Mar9-08, 02:40 PM
1. The problem statement, all variables and given/known data
I am given a line integral:

\int (x^2+y^2)^2ds, where C is a circle of radius 3 with centre in (0;0).

Evaluate it.

3. The attempt at a solution
Ok, first I know (x^2+y^2)^2 = 81. So far, so good.

Then I know for an object in the xy-plane, ds = r*dr*d\theta. I just insert and use the correct limits, and do the integral?

Thanks in advance.

Niles
Mar9-08, 03:10 PM
No, I am totally wrong.

ds is _not_ what I wrote above, but ds = |r'(t)|dt.